The invention relates to an improved process for the preparation of thioglycols.
Processes for the preparation of thioglycol (2-mercaptoethynol) are known. For example, when ethylene oxide and hydrogen sulphide are reacted 2-mercaptoethanol is formed in yields of only 60% (compare F.N. Woodward Chem. Soc. (London) 1948, 1892). The yields are even poorer when, according to German Patent Specification 486,079, ethylene chlorohydrin and sodium bisulphide solution are used as the starting materials. Furthermore, it is known from U.S. Pat. No. 2,402,665 to prepare 2-mercaptoethanol in a technically involved process by high pressure hydrogenation of bis-(2-hydroxyethyl) trisulphide over cobalt sulphide catalysts. The known processes have the disadvantage that they either lead to undesired by-products or the products are accessible only by complicated and technically involved processes.